Evaporable foam casting procedures have been used in casting metal engine blocks for internal combustion and other engine components. In a typical evaporable foam casting process, a pattern, which is identical in configuration to the metal part to be cast, is formed of an evaporable foam material, such as polystyrene. In the casting procedure, the pattern is placed in a mold and a flowable material, such as sand, is introduced into the mold around the pattern and also fills the cavities within the pattern.
A molten metal, such as an aluminum alloy, is introduced to the pattern via a sprue and the heat of the molten metal will vaporize the pattern with the vapor entering the interstices of the sand while the molten metal will fill the void created by vaporizaton of the pattern to provide a cast metal part which is identical in configuration to the foam pattern.
Evaporable foam casting has advantages over conventional sand casting procedures in that it is less costly, and more dimensionally accurate parts can be obtained. Moreover, certain complex configurations may be castable using evaporable foam techniques, while such parts cannot be cast using sand casting techniques.